1. Field of the Invention
This invention relates to improvements in the art of playing back a color video signal recorded in the form of separate luminance and color component signals on a recording medium, and is particularly adapted, though not exclusively so, to the playing back of such component signals derived from a still image and recorded on separate tracks on a pliable magnetic disk.
2. Description Relative to the Prior Art
In the video recording art, luminance and color component signals for a field of a video image are either recorded in combination on a single magnetic track or separately on two or more tracks, that is, two tracks if all the color is contained in one signal or more than two tracks if the color is split between several signals, for example, between red-luminance and blue-luminance signals. If the luminance and color component signals are recorded in combination on a single track, the color component signal is either placed in a vacant location in the frequency spectrum occupied by the video image or interleaved between the energy bands of the luminance component signal. Having the component signals on the same track often leads to undesirable effects. In particular, there is likely to be interference between the luminance and color component signals (often called luminance-to-chrominance crosstalk). Also, the bandwidth of the color component signal is necessarily reduced to fit within the recording spectrum.
Having the component signals on separate tracks provides the potential for superior color reproduction. Due to the physical separation of the component signals on the magnetic medium, the problem of interference between luminance and color component signals is practically eliminated. By taking advantage of the greater channel bandwidth made available by recording the color component signal on its own track, the color signal is considerably improved relative to noise.
Despite these advantages, devoting separate tracks to the luminance and color component signals introduces a number of complications into the playback procedure. These include the necessity of simultaneously generating the luminance and color component signals for a field of a video image and the accompanying necessity of processing the separate component signals in similar, parallel electronic circuits. This ordinarily means that a separate playback head must be used to read each component signal. A similar redundancy in the playback circuit is required to process all of the signals. Though simply reducing the number of heads and playback circuitry is a desirable economic objective, an equally important objective is to avoid an undesirable aerodynamic characteristic of a multi-head structure. Particularly as used with a pliable magnetic disk, the ganging together of several heads and flying these heads closely adjacent to the soft, flexible surface of the disk, leads to severe aerodynamic instability. This causes one or more of the heads to lose proper contact with the magnetic medium, thus distorting the reproduced signal and producing a defect in the reproduced image.